This part of the book is a miscellany of topics:

• Chapter 23 is about files and how your app can store data persistently. It also discusses sharing files with the user and with other apps, plus the document architecture and iCloud, and surveys some common file formats.

• Chapter 24 introduces networking, with an emphasis on downloading of data, along with some specialized forms of networking such as on-demand resources and in-app purchases.

• Chapter 25 is about making your code multithreaded.

• Chapter 26 describes how to support undo in your app.

• Appendix A discusses the lifetime event messages sent to your app.

• Appendix B is a catalog of some useful Swift utility functions that I’ve written.

• Appendix C is an excursus on asynchronous code execution.